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This Preliminary Investigations and Report (technical memorandum) has been prepared to identify future wastewater flows and infrastructure needs within the proposed service area outlined in Exhibit A. This memorandum focuses on the development south of Blanco River and does not include land use assumptions or flow projections north of the river or within the City limits. The infrastructure assumptions for conveyance of the wastewater are schematic in nature with measurements taken from existing GIS platforms. The intended use of this memorandum is conceptual, no topographic survey, geotechnical investigations, or easement research has been performed in the preparation of this memorandum.

Executive Summary

This technical memorandum has been prepared to identify future wastewater flows and infrastructure needs within the proposed service area outlined in Exhibit A. This memorandum focuses on the development south of Blanco River and does not include land use assumptions or flow projections north of the river or within the City limits.

In general the topography of the service area slopes west to east. The area south of Blanco River has primarily three watersheds. Exhibit B, the City’s Wastewater Capital Improvement Plan (Jones-Heroy & Associates) identifies three wastewater basins that complement this topography. This exhibit identifies the need for 4 wastewater lift stations south of Blanco River. In this preliminary investigation the concept of conveying the wastewater adjacent to US Hwy. 281 was investigated.

In developing this memorandum, existing data was reviewed to assist in the development of land use projections within the proposed service area. These land use projections and associated acreage were then used to develop average, peak and wet weather wastewater flows. This alignment would require a 15 inch gravity interceptor and two lift stations to keep the depth of the gravity interceptor from exceeding 25 feet. In this study it’s assumed that the second lift station would convey wastewater under Blanco River and discharge into the existing collection system and ultimately be conveyed to the wastewater treatment plant. The scope of this study did not verify if the existing collection system north of Blanco River has the capacity to accept these additional flows.

The engineer’s opinion of probable construction cost was completed for two lift stations and a gravity interceptor. The construction cost estimate includes a engineering design fee of 25 percent of the construction cost and a contingency of 25 percent. The cost estimate does not include costs for easement acquisition, topographical survey, or geotechnical investigations. The assumptions and clarifications for the study and the infrastructure needs are summarized below and explained in greater detail within the memorandum.